1. Field of the Invention
The invention relates an optical apparatus including an evacuating lens mechanism.
2. Description of the Related Art
In conventional lens barrel, a slide lens which is a part of a lens unit evacuates from an optical axis when retracting so as to thin retracting thickness of the lens barrel for miniaturization of the lens barrel.
Japanese Patent Laid-Open No. 2011-59331 discloses a lens barrel including a first lens group, a second lens group, a third lens group, and a fourth lens group. The third lens group includes a base plate which is reciprocated along an optical axis by a cam follower mechanism, and a lens holder which holds a lens and is swingably supported relative to the base plate. The lens holder is rotatably urged to a center of the optical axis by a torsion spring when shooting, and abuts against an abutting portion provided on the base plate so as to maintain the lens on the optical axis. A cam surface formed on the lens holder abuts against protruding portion protruding from a sensor holder which holds an image pickup element in an optical axis direction, and as a result, the lens holder rotates in a direction of resisting an urging force of the torsion spring and evacuates from the optical axis when retracting. One cam follower pin of three cam follower pins formed on the fourth lens group which is moved by the cam is positioned at one side by the spring for stable optical performance.
However, in Japanese Patent Laid-Open No. 2011-59331, the fourth lens group between the sensor holder and the third lens group needs to avoid the protruding portion so that the protruding portion protruding from the sensor holder evacuates the third lens group. As a result, a light leakage may be generated from the part avoided the protruding portion. If the protruding portion is formed on the fourth lens group, the generation of the light leakage is prevented, but the urging force of the torsion spring applied to the protruding portion formed on the fourth lens group when evacuating the third lens group may be larger than spring force of the cam follower pin. As a result, since the lens group wobbles in the lens barrel and a position of the protruding portion is instability, precise evacuating lens mechanism may not be achieved.